This invention relates to a hinge device and in particular to a seat having an arm rest supported thereon by means of a hinge device.
More particularly, the hinge device is of the type which incorporates a ratchet mechanism and which is operable to support a hinged part at any selected one of a plurality of rotational positions, each defined by engagement of a pawl with a different tooth of the ratches mechanism, the hinge mechanism including means operable after the pawl has ratcheted across the teeth of the ratchet to hold the pawl out of engagement with the ratchet teeth and thereby allow the hinged part to be rotated in the opposite direction until the pawl has cleared the ratchet teeth in said opposite direction. Such a hinge mechanism will be referred to hereinafter on occasion, as being `of the type described`.
Hinge mechanisms of the type decribed have been proposed hitherto, but there is a requirement for a design of such as hinge mechanism which is robust and reliable with a view to providing trouble-free operation over a long period of time in situations in which it is liable to receive rough usage.
The application for which the hinge mechanism of the present invention is particularly intended is to support an armrest on the back of a vehicle seat in such a way as to enable the inclination of the armrest relative to the back of the seat to be varied according to the inclination of the back of the seat, and also to enable the armrest to be dropped down to an inoperative position in which it does not obstruct a person wishing to occupy or leave the vehicle seat.